Could Confirm Spirometric Evaluation Findings, However
Senior Airman Ana Decarvalho, 104th Medical Group aerospace medical technician, performs a spirometry test with Joe D’Astous, 104th Fighter Wing student flight member, in 2019 at Barnes Air National Guard Base, Massachusetts. U.S. Air National Guard photo by Airman 1st Class Randy Burlingame
FORT SAM HOUSTON, TX — When evaluating airway obstruction in military personnel after deployment, impulse oscillometry (IOS) may serve as an additional diagnosis tool, but it can’t replace the reliability of the standard spirometric evaluation, according to a recent study.
The study published in the journal Military Medicine evaluated the usefulness of IOS in diagnosing airway obstruction in military patients undergoing multiple pulmonary function testing (PFT) studies.1
The study authors are affiliated with Brooke Army Medical Center in Joint Base San Antonio (JBSA) Fort Sam Houston, TX, and Walter Reed National Military Medical Center in Bethesda, MD.
The investigators wanted to study IOS because it might be better at detecting peripheral airway disease than spirometry, which mainly focuses on central airways. IOS has potential advantages over spirometry, such as being more portable and relatively simple in comparison. The relative simplicity and portability of IOS equipment could make it valuable in large population screenings and in deployed settings, Michael J. Morris, MD, pulmonary/critical care staff and assistant dean of research at Brooke Army Medical Center, told U.S. Medicine.
In this study, 360 military personnel who were referred for deployed-related pulmonary symptoms underwent a standardized evaluation at Brooke Army Medical Center and Walter Reed National Military Medical Center over a 5-year span. The evaluation included laboratory tests, high-resolution computed tomography imaging, cardiac evaluation with electrocardiogram and echocardiography. PFT consisted of full PFTs, forced inspiratory/expiratory pressures, post-spirometry bronchodilator testing, IOS, exhaled nitric oxide and methacholine challenge testing, the study explained.
The investigation was part of the Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III study.
“Our study suggests that IOS may be a useful addition to spirometry in evaluating military personnel with respiratory symptoms after deployment, but it is not as effective as spirometry and cannot replace it,” Morris said. “IOS has advantages over spirometry, as it only requires passive respiration, but due to its low sensitivity, it should only be considered as an adjunct to spirometry. Additionally, our study highlighted the need for further research to develop more reliable predictive equations for IOS, especially considering gender differences.”
The study’s primary finding was that IOS is not a replacement for spirometry but does offer certain benefits in terms of large population screening, portability, ease of use and, when used alongside spirometry, can be a useful tool for long-term assessment for members complaining of chronic respiratory symptoms, explained Jess T. Anderson, a major in the U.S. Air Force Medical Corps and pulmonary/critical care staff at Brooke Army Medical Center.
Based on the findings, the authors suggest that healthcare professionals who are treating military personnel with deployed-related pulmonary symptoms consider the following recommendations, said Mateo C. Houle, a major in the U.S. Army Medical Corps and pulmonary/critical care staff at Brooke Army Medical Center.
- Spirometry remains the gold standard for assessing lung function and should be the primary diagnostic tool for evaluating airway obstruction.
- Consider IOS as an adjunct if spirometry results are normal but the patient continues to experience respiratory symptoms, particularly exertional dyspnea. IOS may help detect peripheral airway dysfunction that spirometry might miss.
- Interpret IOS results with caution, particularly its lower sensitivity compared to spirometry. A normal IOS result does not necessarily rule out airway obstruction.
- Be mindful of gender differences. The study suggests that IOS may be less reliable in females.
- Always interpret IOS results in conjunction with the patient’s history, physical examination and other clinical findings. Don’t rely solely on IOS results for diagnosis.
- Consider other diagnostic modalities such as chest CT scan, methacholine challenge testing, exercise testing and/or consultation with a pulmonologist.
The original STAMPEDE III study was conducted at Brooke Army Medical Center and Walter Reed National Military Medical Center from 2012 to 2018. The intent of the study was to prospectively evaluate military personnel with chronic respiratory symptoms related to Southwest Asia deployment, Morris pointed out.
During the comprehensive evaluation, 380 study participants underwent a standardized evaluation to include PFT, IOS, chest imaging, echocardiography, bronchoprovocation testing, exercise testing and bronchoscopy. The initial study results were published in the journal Chest in 2020.2
“This study found that exertional dyspnea was the most common diagnosis followed by asthma, airway hyper reactivity and upper airway disorders,” Morris said. “This cohort notably had numerous comorbidities to include allergies, reflux, obesity, mental health disorders and sleep disorders that may have contributed to their overall symptom complex.”
The authors also published STAMPEDE I in the American Journal of Respiratory and Critical Care Medicine in 2014.3 STAMPEDE II was published in Respiratory Care in 2019.4 Morris noted that the current study in Military Medicine was an analysis of the spirometry and IOS values derived from the STAMPEDE III study.
“This study provides a snapshot of respiratory health at a particular point in time,” Morris explained. “Longitudinal studies are needed to assess the long-term impact of deployment-related exposures on lung function and to determine if IOS can be used to track disease progression or response to treatment over time. This is particularly important, given the concerns about chronic effects of exposures.”
“Additionally, the study highlights the limitations of current IOS reference values. Further research is needed to refine IOS techniques and establish more reliable predictive equations, considering factors like age, gender and ethnicity,” Morris suggested.
- Houle MC, Cavacece CT, Gonzales MA, Anderson JT, Hunninghake JC, Holley AB, Morris MJ. Correlation of Impulse Oscillometry with Spirometry in Deployed Military Personnel with Airway Obstruction. Mil Med. 2023 Nov 8;188(Suppl 6):400-406. doi: 10.1093/milmed/usad171. PMID: 37948261.
- Morris MJ, Walter RJ, McCann ET, Sherner JH, Murillo CG, Barber BS, Hunninghake JC, Holley AB. Clinical Evaluation of Deployed Military Personnel With Chronic Respiratory Symptoms: Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III. Chest. 2020 Jun;157(6):1559-1567. doi: 10.1016/j.chest.2020.01.024. Epub 2020 Feb 1. PMID: 32017933.
- Morris MJ, Dodson DW, Lucero PF, Haislip GD, Gallup RA, Nicholson KL, Zacher LL. Study of active duty military for pulmonary disease related to environmental deployment exposures (STAMPEDE). Am J Respir Crit Care Med. 2014 Jul 1;190(1):77-84. doi: 10.1164/rccm.201402-0372OC. PMID: 24922562.
- Morris MJ, Skabelund AJ, Rawlins FA 3rd, Gallup RA, Aden JK, Holley AB. Study of Active Duty Military Personnel for Environmental Deployment Exposures: Pre- and Post-Deployment Spirometry (STAMPEDE II). Respir Care. 2019 May;64(5):536-544. doi: 10.4187/respcare.06396. Epub 2019 Jan 8. PMID: 30622173.
